This invention relates to an anticholesteremic agent or a cholesterol level-lowering agent and, more particularly, it is concerned with an anticholesteremic agent comprising as a main component a strongly basic anion exchange resin having imidazolium salts as functional groups.
It has already been known that an anion exchange resin is applicable as the so-called anticholesteremic agent for lowering a blood cholesterol level (U.S. Pat. Nos. 3,499,960 and 3,780,171 and British Pat. No. 929,391 and Japanese Patent Laid-Open Application No. 10386/1978). The mechanism that administration of an anion exchange resin could lower blood cholesterol may be considered as stated below. Namely, a basic anion exchange resin would adsorb and fix bile acids present in the intestine to prevent said bile acids from reabsorption and to promote conversion of cholesterol, which is equilibrated with bile acids in the liver, to bile acids, whereby blood cholesterol lowered.
A representative basic anion exchange resin, which has been hitherto applied as an anticholesteremic agent, is an ion exchange resin having aliphatic quarternary ammonium salts as functional groups (U.S. Pat. Nos. 3,499,960 and 3,780,171). However, such anion exchange resin has drawbacks of a large dosage (8 to 16 g/day) and difficulty in ingestion due to its low activity.
Also, the anion exchange resin having aliphatic quaternary ammonium salts as functional groups can be prepared by reacting an aliphatic tertiary amine with a haloalkyl group introduced onto a cross-linked polymer, but the resultant anion exchange resin bears an offensive odor characteristic of aliphatic amine and would not be put into practical use as such. Then, decrease in such offensive odor has been attempted practically by coating the surface of said anion exchange resin, but increase in dosage should be unavoidable due to a reduced ion exchange capacity caused by surface coating.
In order to solve these drawbacks, the present inventors had already developed an anticholesteremic agent using as a main component an anion exchange resin prepared by using imidazoles for forming an anion exchangeable group, as filed in Japanese Patent Laid-Open Application No. 24310/1982.
The above invention could overcome the prior difficulties, but a far higher active product has been desired.
Namely, the anion exchange resin of the above invention is prepared by reacting a halomethyloxirane compound with an imidazole and then reacting the resultant modified imidazole with a polyfunctional epoxy compound. However, said modified imidazole is a mixture of imidazole, 1:1 or 1:2 adduct of imidazole and halomethyloxirane compound, and an oligomer, and further is not separable so that the resultant anion exchange resin has a less content of the imidazolium salt capable of contributing to salt-splitting power among basic exchangeable groups upon imidazole and, though a higher activity can be seen as compared with the prior product, a far more highly active product has been desired.